The present invention is in the field of wellhead equipment and is intended for use in oil wells, where extraction is carried out by using pumping equipment with reciprocating sucker rods. This invention is used to rotate a string of sucker rods during the operation of pumping equipment.
The overwhelming majority of oil wells have either intended or unintended deviation from the vertical axis. Rod rotators and tubing rotators are used in order to decrease the wear of strings of oil well tubings and sucker rods, prevent unwanted unscrewing of sucker rods and reduce the deposit of wax and paraffin on the surfaces of tubings and sucker rods.
Rod rotators such as Hercules by R&M Energy Systems or RODEC are firmly attached to the upper part of polished rod through a central hole in the body. There is a ratchet-type converting mechanism (worm shaft) inside the body. This mechanism is activated using an actuator lever. One end of this lever sits on an intake shaft and is outside of the body, and the other end is connected with the front arm of walking beam of pump jack through actuator cable.
This type of a device forms a 4-member linkwork. The first member is an upper part of polished rod that is suspended on the head of a walking beam using a cable. The second element is a part of the front arm of the walking beam. The third part is the flexible actuator cable, and the fourth element is an actuator lever of rod rotator. The rod rotator becomes a hinge, which converts limited angular movement of the members into a rotating movement, and thus, turns polished rod along with a string of sucker rods in a perpendicular plain to a certain angle. It is this angle of the turn of string of sucker rods that is supposed to change the point of contact between the tubing and sucker rods, to avoid the contact of tubing with sucker rods in the same spot and thus increase wear resistance of both wearing parts.
This method of using rod rotators in pumping equipment is less effective for several reasons. Below are some of these reasons.                The degree of the rotation angle of polished rod is very small and within the elasticity range of the sucker rod string-cable suspension. The gear ratio of rod rotators is within 30-40 degrees. At an actuator lever's effective rotation angle of 15-20 degrees, the rotation angle of polished rod can have a maximum value of 0.1-0.4 degrees.        The maximum tension of actuator cable can be achieved only at the end of the walking beam's movement down. This means that the force necessary to rotate the polished rod appears only after the movement is either completed or coming to an end.        The force applied to the actuator lever of rod rotator is located at some distance from the axis of polished rod. This leads to the moment of force that constantly pulls polished rod in the same direction. Consequently, this situation results in the accelerated wear of sealing packers of wellhead stuffing box that seal the head of the well and thus, necessitate frequent replacement of sealing packers.        
Hence, the aforementioned rod rotators can achieve only one objective out of three that we mentioned above. Namely,                1. They can achieve the objective of preventing unwanted unscrewing of string of sucker rods        2. They do not achieve the objective of increasing wear resistance of wearing equipment        3. They do not achieve the objective of decreasing the deposits of wax and paraffin on the walls of tubing and sucker rods.        
It was the result of the lack of effective engineering solutions to achieve the abovementioned objectives for rod rotators that led the main engineering thoughts on tube rotators to focus on attaining the same objectives.
The known US patents on tubing rotators cited in the References have one common design basis. It is activation of tubing rotator from walking beam with flexible cables and further conversion of angular movement into rotation in a perpendicular plane. In other words, this is exactly the same as the mode of usage and engineering approach to rod rotators with minute differences.
Tubing rotators are used to achieve the last two objectives mentioned above. However, this approach comes with the following shortcomings:                Correlation of the masses of sucker rods and tubing is within 1:4 and 1:5. This fact explains the inevitable increase in tubing rotators' mass. Energy spent by tubing rotators in order to achieve necessary rotation torques of tubing strings is substantial and is 5 to 10 times higher than that of rod rotators.        Length of time needed to install a tubing rotator at a wellhead is approximately several hours, while it takes only an hour to install a rod rotator.        As a tubing rotator's mass considerably exceeds that of a rod rotator, the fabrication, transportation, service and other costs of two parts are quite different.        
We have to note that all known forms of tubing rotators work according to the same principle as rod rotators: they are all activated by an arm of the walking beam of pumping equipment. The only difference is that the installation of tubing rotators is done on wellhead flange of casing string for all types of tubing rotators. This leads to the shift of the kinematical scheme from 4 members in rod rotators to 3 members in tubing rotators. But the activation method remains intact—activation from the arm of the walking beam.
The present invention solves this problem in a radically different manner. In other words, the invention does not involve the activation of rod rotator using arm of walking beam of pumping equipment.
The present invention solves the problem in such a way that a string of sucker rods activates rod rotator. This allows obtaining larger results from the rotation torque of the string of sucker rods as well as larger rotation angles in tens of degrees that are not possible in existing technologies of rod rotators. We have to note that known tubing rotators do not have this type of rotation angle either.
The present invention achieves the three objectives mentioned above more effectively and comprehensively.